1. Field of the Invention
The present invention relates to flow-control servo-devices for a hydraulic system, especially for the power-assisted steering of a vehicle, comprising a pressure source having an outlet connected to an inlet of a hydraulic distributor of the open center type for controlling a hydraulic motor, the distributor having a return outlet towards a tank and, more particularly, a device of the type comprising, in a body, a slide modulator assembly inserted in a branch circuit between the outlet of the pressure source and the tank and controlled hydraulically, as a result of a pressure differential effect, by an electromagnetically controlled pilot valve generating the pressure differential.
2. Description of the Prior Art
A flow-control device of this type is described in the document EP-A-0 072 732 in the applicant's name. In the device of that document, the pilot valve is arranged between the pilot chamber of the slide modulator and the outlet to the tank, thereby modulating a leakage flow which is a function of the pilot pressure which itself varies as a function of the fluctuations at the outlet of the pressure source, the arrangement being difficult to adjust and requiring relatively sophisticated electronics for controlling the pilot valve.